Methanogens Methanogens are anaerobic archaea that produce methane as a byproduct of their energy metabolism, i.e., catabolism. Methane production, or methanogenesis, is the only biochemical pathway for ATP generation in methanogens. All known methanogens b ...

are a group of

microorganisms A microorganism, or microbe, is an organism of microscopic size, which may exist in its single-celled form or as a colony of cells. The possible existence of unseen microbial life was suspected from antiquity, with an early attestation in ...

that produce

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The abundance of methane on Earth makes ...

as a byproduct of their metabolism. They play an important role in the digestive system of

ruminants Ruminants are herbivorous grazing or browsing artiodactyls belonging to the suborder Ruminantia that are able to acquire nutrients from plant-based food by Enteric fermentation, fermenting it in a specialized stomach prior to digestion, principa ...

. The

digestive tract The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the Digestion, digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascula ...

of ruminants contains four major parts:

rumen The rumen, also known as a paunch, is the largest stomach compartment in ruminants. The rumen and the reticulum make up the reticulorumen in ruminant animals. The diverse microbial communities in the rumen allows it to serve as the primary si ...

reticulum Reticulum is a small, faint constellation in the southern sky. Its name is Latin for a small net, or reticle—a net of crosshairs at the focus of a telescope eyepiece that is used to measure star positions. The constellation is best viewed b ...

omasum The omasum, also known as the green, the fardel, the manyplies and the psalterium, is the third compartment of the stomach in ruminants. The omasum comes after the rumen and reticulum and before the abomasum. Different ruminants have different oma ...

and

abomasum The abomasum, also known as the maw,The Cham ...

. The food with saliva first passes to the rumen for breaking into smaller particles and then moves to the reticulum, where the food is broken into further smaller particles. Any indigestible particles are sent back to the rumen for rechewing. The majority of anaerobic microbes assisting the cellulose breakdown occupy the rumen and initiate the fermentation process. The animal absorbs the fatty acids, vitamins and nutrient content on passing the partially digested food from the rumen to the omasum. This decreases the pH level and initiates the release of enzymes for further breakdown of the food which later passes to the abomasum to absorb remaining nutrients before excretion. This process takes about 9–12 hours. Some of the microbes in the ruminant digestive system are: *'' Fibrobacter (Bacteroides) succinogenes'' is a

gram negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists of ...

, cellulolytic and amylolytic methanogen that produces formates, acetates and succinates. *'' Ruminococcus albus'' is a cellulolytic, xylanolytic bacterium producing ethanol, hydrogen, carbon dioxide, formates and acetates. *'' Ruminococcus flavefaciens'' is a cellulolytic, xylanolytic bacteria producing formates, acetates, hydrogen and succinates. *'' Butyrivibrio fibrisolvens'' is a proteolytic, cellulolytic, xylanolytic microbe producing lactate, butyrate, ethanol, hydrogen, carbon dioxide, formates and acetates. *'' Streptococcus bovis'' is an amylolytic, major soluble sugar

ferment Fermentation is a type of anaerobic metabolism which harnesses the redox potential of the reactants to make adenosine triphosphate (ATP) and organic end products. Organic compound, Organic molecules, such as glucose or other sugars, are Catabo ...

er, proteolytic, microbe resulting in lactate, acetate and formate. *'' Ruminobacter (Bacteroides) amylophilus'' amylolytic, propionate, proteolytic, organism that forms,

formate Formate (IUPAC name: methanoate) is the conjugate base of formic acid. Formate is an anion () or its derivatives such as ester of formic acid. The salts and esters are generally colorless. Fundamentals When dissolved in water, formic acid co ...

s, acetates and succinates. *'' Prevotella (Bacteroides) ruminocola'' amylolytic, xylanolytic, propionate, proteolytic, microbe that creates, formates, acetates, succinates and propionate. *'' Succinimonas amylolytica'' amylolytic, dextrinolytic, bacteria forming

acetate An acetate is a salt formed by the combination of acetic acid with a base (e.g. alkaline, earthy, metallic, nonmetallic, or radical base). "Acetate" also describes the conjugate base or ion (specifically, the negatively charged ion called ...

s and

succinate Succinic acid () is a dicarboxylic acid with the chemical formula (CH2)2(CO2H)2. In living organisms, succinic acid takes the form of an anion, succinate, which has multiple biological roles as a metabolic intermediate being converted into Fuma ...

s. *'' Selenomonas ruminantium'' amylolytic, major soluble sugar fermenter, glycerol-utilizing, lactate-utilizing, proteolytic, microbe producing acetates, lactates, hydrogen, carbon dioxide and propionates. *'' Lachnospira multiparus'' propionate, proteolytic, A microbe that results in production of lactate, ethanol, hydrogen, carbon dioxide, formates and acetates. *'' Succinivibrio dextrinosolvens'' propionate, dextrinolytic, bacteria forming formates, acetates, lactates and succinates *'' Methanobrevibacter ruminantium'' methanoic, hydrogen utilizing, archaea involved in the creation of methane *''

Methanosarcina barkeri ''Methanosarcina barkeri'' is the type species of the genus ''Methanosarcina'', characterized by its wide range of substrates used in methanogenesis. While most known methanogens produce methane from H2 and CO2, ''M. barkeri'' can also dismutate ...

'' methanoic, hydrogen utilizing, archaea involved in the creation of methane and carbon dioxide.

References

{{Reflist Ruminants Microorganisms Digestive system Methane